1. Field of the Invention
This invention relates to a volume controller for controlling outputting of a volume of an inputted voice.
2. Related Background Art
A gain control of an exchange is performed hitherto according to a construction shown in FIG. 1. FIG. 1 then represents a construction of a prior art digital private branch exchange.
In FIG. 1, a reference numeral 81 denotes an exchange, 82 denotes a control portion thereof, 83 denotes a time switch, 84 denotes a timing circuit, 85 denotes a station line interface, 86 denotes a PCM codec, 87 denotes an operational amplifier, 88 denotes a gain change-over switch, 89 denotes an extension interface, 90 denotes a forward PCM highway, 91 denotes a backward PCM highway, 92 denotes a telephone network, 93 denotes an exchange, and 94 denotes a 2/4 line converting portion.
Here, an analog signal from the telephone network 92 has been subjected so far to gain control by modifying a resistance value connected to the operational amplifier 87 on the change-over switch 88 according to a control from the control portion 82. Then, such gain control is carried out likewise in the case of an extension interface and other circuit interface.
However, since a gain control is effected at every circuit in the above-described prior art, a defect is quite unavoidable such that a multitude of circuits must be controlled according particularly as the circuits increase in number, thus complicating hardware structurally.